1. Field of the Invention
The present invention relates to a rotation angle detecting device that detects the rotation angle of a rotating object.
2. Description of the Related Art
JP-A-2003-75108 discloses a prior art rotation angle detecting device that is constructed of a disk-shaped permanent magnet and two or three magnetic sensors. The magnetic sensors are respectively disposed at portions to confront the permanent magnet so as to generate output signals according to the magnetic field strength. A rotation angle of a rotating object is calculated by a certain arithmetic expression based on the output signals of the magnetic sensors. However, it is impossible for such a prior art rotation angle detecting device to detect a rotation angle if one of the magnetic sensors fails.